openstack 实例只支持状态为active，stopped，error的实例进行救援，所以如果是其他状态的实例需要evacuate，则需要重置状态。
校验实例所在物理主机状态为down，并且实例状态为active,stopped,error才能执行evacuate并创建该实例的迁移任务
1，重置实例状态
实例i：c5dcb2c2-9ce4-463a-94b9-1c1615d37084
nova reset-state c5dcb2c2-9ce4-463a-94b9-1c1615d37084 --active
2，扩散实例到nova-28.os上
nova evacuate c5dcb2c2-9ce4-463a-94b9-1c1615d37084 nova-28.os
3，重启实例
nova stop c5dcb2c2-9ce4-463a-94b9-1c1615d37084 nova start c5dcb2c2-9ce4-463a-94b9-1c1615d37084
通过openstack迁移
1. 查看实例信息
openstack server list --long
| ID | Name | Status | Networks | Host |
+--------------------------------------+------------------+--------+----------------------------+--------------------+
| 5b9e1a99-d73f-46e3-acf4-c31a58c4e09a | test1 | ACTIVE | lan-ceshi=10.200.40.237 | nova05 |
2. 查看主机信息
openstack hypervisor list
+-----+---------------------+-----------------+--------------+-------+
| ID | Hypervisor Hostname | Hypervisor Type | Host IP | State |
+-----+---------------------+-----------------+--------------+-------+
| 3 | nova05 | QEMU | 10.10.100.12 | down |
| 6 | nova06 | QEMU | 10.10.100.11 | up |
3. 迁移
openstack server migrate --live-migration nova06.avlyun.org 5b9e1a99-d73f-46e3-acf4-c31a58c4e09a ... openstack server list --long
| ID | Name | Status | Networks | Host |
+--------------------------------------+------------------+--------+----------------------------+--------------------+
| 5b9e1a99-d73f-46e3-acf4-c31a58c4e09a | test1 | ACTIVE | lan-ceshi=10.200.40.237 | nova06 |
注意： 通过openstack server migrate 迁移，两个主机的cpu参数需要一致。如果cpu不一样，会出现“ Unacceptable CPU info: CPU doesn't have compatibility ”。
解决：
# vim /usr/lib/python2.7/site-packages/nova/virt/libvirt/driver.py
注释掉cpu检测
# Compare CPU
"""
if not instance.vcpu_model or not instance.vcpu_model.model:
source_cpu_info = src_compute_info['cpu_info']
self._compare_cpu(None, source_cpu_info, instance)
else:
self._compare_cpu(instance.vcpu_model, None, instance)
"""